POS1091 LESS RADIOGRAPHIC SPINAL DAMAGE IN PSORIATIC ARTHRITIS PATIENTS COMPARED TO SpA PATIENTS
Authors: M. De Hooge, A. Ishchenko, A. S. De Craemer, S. Steinfeld, A. Nzeusseu Toukap, D. Elewaut, R. Lories, F. Van den Bosch, K. De Vlam
Journal: Annals of the Rheumatic Diseases (2022)

Background Psoriatic arthritis (PsA) is an inflammatory joint disease that is traditionally included in the Spondyloarthritis (SpA) spectrum. Prevalence and impact of axial involvement in PsA remain understudied but increasingly affect treatment decisions. Objectives A step towards fathoming this issue is to report on baseline radiographic spinal damage in PsA and SpA patients (pts) from 2 prospective multicentre cohort studies in private and academic rheumatology practices. Methods Data on PsA pts were from the Belgian Epidemiological Psoriatic Arthritis Study (BEPAS); prospective multicentre cohort in 17 Belgian rheumatology practices. Recruitment was Dec2012-Jul2014. Pts were included when fulfilling the Classification criteria for Psoriatic Arthritis (CASPAR). SpA pts were from a Belgian observational cohort (Be-Giant) of SpA pts fulfilling the ASAS SpA classification criteria. Radiographs of the spine were obtained at baseline and after 2 years. Two calibrated readers evaluated radiographic damage by assessing modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). Readers were blinded for time sequence, clinical data and information from other obtained images (radiographs of hands, feet, sacroiliac joints). Consensus scores are described. Results In total 461 pts were included in BEPAS. Mean age was 52.79±12.29 years and 43.0% (n=198) were female; average disease duration was 8.5 ± 9.3 years and approximately 34% of the pts reported inflammatory axial pain. From 312 pts spinal radiographs were obtained. At baseline, the vast majority of PsA pts had an mSASSS of 0 (n=273, 87.5%), according to both readers. In 33 PsA pts (10.6%) mSASSS was 2 or more. For the SpA pts percentages were lower but the trend was similar (see Figure 1). Though lesser pts showed abnormalities, the SpA pts with spinal damage show a higher mSASSS, therefore indicating more spinal damage then the PsA pts (p&lt;0.05). Both patient groups show some outliers with high mSASSS, increasing the average mSASSS especially in the SpA cohort (mean mSASSS = 9.1±14.11) compared to the median of 3 (IQR 2-6) in both cohorts Syndesmophytes are seen in 10.6% and 6.2% of the PsA and SpA pts, respectively. Similar to the mSASSS, SpA pts had more syndesmophytes (mean: 4.4±5.50) compared to PsA pts (mean 2.0±1.45); p&lt;0.05. PsA pts had more often syndesmophytes located in the cervical spine (24/35, 68.6%) compared to the SpA patient group (9/21, 42.9%); p&lt;0.05. Erosions and especially sclerosis and squaring are uncommon in both patient groups. Conclusion Spinal damage is seen in approximately 10% or less of both PsA and SpA pts in these cohorts. SpA pts show higher mSASSS values and more syndesmophytes as compared to the PsA pts. Syndesmophytes in PsA pts are more often located in the cervical spine while the location is more equally distributed in SpA pts. Table 1. Spinal damage at baseline of patients from the BEPAS (PsA patients) and Be-Giant (SpA patients) cohorts PsA patients (n=312 ) SpA patients (n=260 ) PsA patients (n=312 ) SpA patients (n=260 ) mSASSS ≥2, no of patients 33 (10.6%) 19 (7.3%) Syndesmophytes (total spine ) 33 (10.6%) 16 (6.2%) mSASSS ≥1, no of patients 39 (12.5%) 22 (8.5%) mean, (SD) 2.0 (1.45) 4.4 (5.50) mean, (SD) 4.5 (4.24) 9.1 (14.11) min, 0.25, median, 0.75, max 1.0 1.0 2.0 2.0 8.0 1.0 1.0 2.5 5.0 22.0 min, 0.25, median, 0.75, max 1.0 2.0 3.0 6.0 21.0 1.0 2.0 3.0 10.0 64.0 Syndesmophytes (cervical spine ) 24 (7.7%) 9 (3.5%) Erosions ≥1, no of patients 13 (4.2%) 5 (1.9%) mean, (SD) 1.8 (1.32) 2.9 (2.89) mean, (SD) 1.5 (1.39) 1 (0.0) min, 0.25, median, 0.75, max 1.0 1.0 1.0 2.0 7.0 1.0 1.0 2. 0 3.0 10.0 min, 0.25, median, 0.75, max 1.0 1.0 1.0 1.0 6.0 1.0 1.0 1.0 1.0 1.0 Syndesmophytes (lumbar spine ) 11 (3.5%) 12 (4.6%) Squaring ≥1, no of patients No obs. 4 (1.5%) mean, (SD) 1.9 (0.70) 3.7 (4.21) mean, (SD) No obs 1.8 (0.96) min, 0.25, median, 0.75, max 1.0 1.0 2.0 2.0 3.0 1.0 1.0 1.0 5.0 12.0 min, 0.25, median, 0.75, max No obs 1.0 1.0 1.5 2.5 3.0 Sclerosis ≥1, no of patients 2 (0.6%) 6 (2.3%) mean, (SD) 1.5 (0.71) 1.8 (1.33) min, 0.25, median, 0.75, max 1.0 1.0 1.5 2.0 2.0 1.0 1.0 1.0 3.0 4.0 Acknowledgements The BEPAS study has been supported by MSD Belgium, with noteworthy mentioning of Hermine Leroi. Disclosure of Interests None declared